1042 AQUATIC PHYCOMYCETES 



proliferous, often forming a wavy or helicoid discharge 

 tube several times the length of the sporangium and 2-3 \i 

 in diameter; zoospores infrequently formed exogenously, 

 typically within a vesicle; hyphae less than 1.5 \j. in diam- 

 eter; in vegetable debris P. diacarpum Butler, p. 124m 



Sporangia not proliferating 



Sporangia catenulate often up to thirteen in a series, spherical, 

 18-24 [jl in diameter, sessile or separated by short stalks; 

 mycelium 2-6 \i in diameter, coenocytic when young, sep- 

 tate when mature; in soil P. intermedium de Bary, p. 125m 



Sporangia not catenulate, terminal or intercalary, not prolifer- 

 ating, spherical, pyriform, cylindrical or curved, when 

 spherical measuring 12-50 \x, in diameter, when cylindrical 

 up to 65 [l long; zoospores formed in a vesicle at the tip of a 

 very long discharge tube, 10-12 \i by 6 \i; sporangia also 

 germinating by germ tubes; in soil 



P. elongatum Matthews, p. 126m 



See also the following imperfectly known species of Pythium on 

 aquatic hosts : 



P. akanense Tokunaga, Trans. Sapporo. Nat. Hist. Soc, 12: 119-123. 1932. 



On Aegagropila sauteri. 

 P. charaeearum de Wild., Ann. Soc. Belg. Micros. (Mem.), 20: 107-136. 



1896. On oogonia of Chara sp. 

 P. daphnidarum Petersen, Bot. Tidssk., 29:345-440. 1909. On Daphnia 



and Bosmina. 

 P. hydrodictyorum de Wild., Ann. Soc. Belg. Micros., 21 : 22. 1897. On Hy- 



drodictyon. 



Note: The fungus from saline habitats, termed P. echinocarpum Ito 

 and Tokunaga by Hohnk (1953a), strongly resembles P. irregular e Buis- 

 man. Hohnk's (1953a) P. imperfectum, a lobulate filamentous sporangial 

 type lacking sex organs cannot, of course, be compared with other 

 species. 



PYTHIOGETON Minden 



Falck, Mykolog. Untersuch. Berichte, 2(2): 241. 1916 



(Fig. 88 p. 1045) 



Mycelium well developed, consisting of delicate much-branched hy- 

 phae, appressoria occasionally formed; zoosporangia terminal or inter- 



